TypeError: Drupal\layout_builder\Entity\LayoutBuilderEntityViewDisplay::save(): Return value must be of type int, null returned

Why remove the return type instead of just making it nullable?

Yes @mstrelan, IMO it would be better.
Added nullable return type. Needs review. Thanks!

None of the parent classes/interfaces have a return type yet, so leaving it out until they do seems safer to me.

The inherited doc says this only returns an int so if that's incorrect that should be fixed as well.

There are existing issues dealing with that, I referenced them in the related issue list.

Not sure we should compound on it. Definitely -1 for changing return type but leaving docs wrong.

I feel like it would take a long time to change EntityInterface::save() to either return nothing or always return an int, because there are a lot of implementations of that method. In order to fix this bug as fast as possible, and to not confuse people or tools like PHPStan looking at the method docs any longer, I propose we just make the return type nullable in the docs. I'll add that to the MR.

DieterHolvoet → closed merge request !8791

After further investigation I found that this specific issue comes from the no_entity_view_display module not returning anything in the save() method. I'll transfer the issue to that project.